1. Field of the Invention
The present invention relates to a gateway apparatus, a control instruction processing method, and a program.
2. Description of the Related Art
Recently, facility networks as networks for control systems in buildings and factories have been increasingly converted into IP-based networks. In IP-based facility networks, people can control facility equipment such as lightings and air conditioners via IP networks. For example, a lighting can be easily ON/OFF-controlled by clicking an image of the lighting displayed on the Web browser of a PC.
In general, a control instruction for facility equipment which is transmitted from a PC is supplied via a gateway and an IP controller. The gateway is located on the boundary between a network for a control system and a network for an OA system. For example, the gateway checks a control authority, and performs protocol conversion. The IP controller is located at the termination of an IP network. The IP controller processes a control instruction transmitted from the gateway and controls the facility equipment.
An IP-based facility network allows many people to simultaneously perform control more easily than the conventional technology (see JP-A 2006-129282 (KOKAI)).
In an IP-based facility network, therefore, there is a possibility of the occurrence of the number of control instructions exceeding the throughput capacity of an IP controller. In this case, the IP controller cannot process all the control instructions, and hence packet loss and the like occur. In addition, wasteful control may be provided for facility equipment. Assume that an air conditioner is performing preparatory operation to start heating operation. In this case, repeatedly performing control to start heating operation will impose an excess load on the facility equipment or the IP controller.
Conventionally, as the number of control instructions increases, the number of control instructions will exceed that can be processed by the IP controller, or wasteful control is provided for facility equipment.